JP4082087B2 - Hydraulic gear pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic gear pump suitably used for hydraulic equipment, cargo handling equipment, welfare equipment and the like.
[0002]
[Prior art]
Conventionally, a double-rotating hydraulic gear pump has a pair of outlets and outlets, and discharges and sucks each other depending on the rotation direction of the drive shaft of the pump. When these are connected to ports of actuators such as a hydraulic cylinder and a hydraulic motor, the operating direction of the actuator can be changed by changing the rotation direction of the pump of the drive shaft.
[0003]
When such a double-rotating gear pump is actually connected to an actuator and used, in a configuration using a general double-rotating gear pump, when the pressure in the hydraulic circuit rises, the relief valve is operated to cause an excess. Although the working fluid is poured into a tank or the like, noise is generated and energy is consumed when the relief valve is operated, which is extremely inconvenient particularly when used in a general household. Therefore, it has been considered to use a low-pressure priority shuttle valve to automatically replenish hydraulic oil when the amount of oil in the circuit is insufficient, thereby suppressing the operation of the relief valve to reduce noise and save energy.
[0004]
[Problems to be solved by the invention]
However, if such a low-pressure priority shuttle valve does not operate sufficiently, hydraulic fluid will not be sufficiently replenished when the amount of fluid in the circuit is insufficient, causing pressure loss, and cavitation due to insufficient fluid pressure. The noise is generated and the efficiency is lowered, and the significance of reducing the noise and energy is reduced by introducing a low-pressure priority shuttle valve. Further, when cavitation occurs, an impact is applied to the gear pump, and the operation becomes unstable.
[0005]
In order to solve the above-described problems, the present invention is configured to sufficiently operate the low-pressure priority shuttle valve.
[0006]
[Means for Solving the Problems]
That is, the hydraulic gear pump according to the present invention is a double-rotating type having a pair of outflow inlets, and includes a pump body having the pair of outflow inlets and a low-pressure priority shuttle valve connected to a tank. In addition, a hydraulic fluid passage in the pump that penetrates from the outflow inlet to the low pressure priority shuttle valve is provided, and the low pressure side of the outflow inlet of the pump body can communicate with the tank. Features .
[0007]
In this way, since the low pressure priority shuttle valve is close to the outflow inlet of the gear pump, the pressure loss can be kept low and cavitation is less likely to occur. Accordingly, noise can be reduced and stable operation can be realized.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
[0009]
The hydraulic gear pump P according to this embodiment includes a pump body 1 and a low-pressure priority shuttle valve 2 as shown in FIG. 1 as a longitudinal sectional view, FIG. 2 as a front view, and FIG. 3 as a rear view. It has a pair of outflow inlets 1a and 1b. And it is used for the hydraulic welfare lifter as described below. As shown in the circuit diagram of FIG. 4, the hydraulic welfare lifter includes a double-acting hydraulic cylinder 3 through the pair of outflow inlets 1a and 1b via an external hydraulic fluid passage A and an external hydraulic fluid passage B. Are connected to the outflow inlets 3a and 3b provided in the bore chamber 31 and the rod chamber 32, and a closed circuit is formed between them to form a normal operation passage. Relief valves 4 a and 4 b are connected to the passage A and passage B as safety valves, respectively, and the working fluid that has passed through the relief valves 4 a and 4 b is returned to the tank 5. The external hydraulic fluid passage A and the external hydraulic fluid passage B are connected to the tank 5 via the low pressure priority shuttle valve 2.
[0010]
The pump body 1 is configured in the same manner as a general hydraulic gear pump, and a pair of gears 14 and 15 are accommodated in a casing 11 in a meshed state. More specifically, the casing 11 is configured by attaching and joining the rear cover 13 to the end face of the body 12 and connecting them with a bolt B1. Hereinafter, the direction is described with reference to the direction from the body 12 side to the rear cover 13 side.
[0011]
As shown in FIG. 5, the body 12 is provided with spectacle-shaped eyeglass holes 12 a, and the drive gear 14 and the driven gear 15 are accommodated in an engaged state. A movable side plate 16 is attached to the side surface of 15 to close the volume space. Further, as shown in FIGS. 2 and 3, the body 12 is provided with bearing holes 12a and 12b. The rotary shafts 141 and 151 having the gears 14 and 15 attached to the bearing holes 12a and 12b are bushed. The bearing is rotatably supported via 17. On the other hand, as shown in FIG. 6 which is a bb sectional view in FIG. 1, the rear cover 13 is provided with bearing holes 13a and 13b, and the gears 14 and 15 are attached to these bearing holes 13a and 13b. The rotary shafts 141 and 151 are rotatably supported via the bush 18. Further, the movable side plate 16 is configured to balance the pressure. Further, an in-pump working fluid passage 10a that reaches the rear end surface through the body 12 and the rear cover 13 from the outflow inlet 1a is provided, and a pump that reaches the rear end surface through the body 12 and the rear cover 13 also from the outflow inlet 1b. An internal hydraulic fluid passage 10b is provided.
[0012]
Then, by applying a driving force from the external input shaft 6 shown in FIG. 1 connected to a motor or the like (not shown) to the rotating shaft 141 of the driving gear 14 having one end extended to the outside, 15 is synchronously reversely rotated, and the working fluid sucked from the outflow inlet 1a is confined in a volume space closed by the teeth of the gears 14 and 15, the movable side plate 16 and the eyeglass hole 12a, and guided to the outflow inlet 1b to be discharged. The pumping action and the pumping action in the reverse direction are performed.
[0013]
The operation of the pump body 1 configured as described above will be described with reference to FIG. When this pump body 1 is operated to push out (extend) the hydraulic cylinder 3 to the right (extend), the liquid in the rod chamber 32 of the hydraulic cylinder 3 circulates into the pump body 1 through the external hydraulic fluid passage B and is discharged therefrom. The hydraulic fluid that has flowed flows into the bore chamber 31 of the hydraulic cylinder 3 through the external hydraulic fluid passage A. That is, the pump main body 1 acts to suck in the hydraulic fluid from the outflow inlet 1b and discharge it from the outflow inlet 1a. However, since the hydraulic fluid flowing out from the rod chamber 32 of the hydraulic cylinder 3 and passing through the external hydraulic fluid passage B is less than the hydraulic fluid passing through the external hydraulic fluid passage A on the discharge side of the hydraulic pump 1, at this time It is necessary to make up for the shortage from the tank 5. Conversely, when the pump body 1 is reversed and the hydraulic cylinder 3 is pulled to the left (retracted), the liquid in the bore chamber 31 of the hydraulic cylinder 3 flows into the pump body 1 through the passage A and is discharged from here. The liquid flows into the rod chamber 32 of the hydraulic cylinder 3 through the passage B. However, since the hydraulic fluid flowing out from the bore chamber 31 of the hydraulic cylinder 3 and passing through the external hydraulic fluid passage A is larger than the hydraulic fluid passing through the external hydraulic fluid passage B on the discharge side of the hydraulic pump 1, at this time It is necessary to return the surplus to the tank 5.
[0014]
Therefore, in this embodiment, the hydraulic fluid passages 10a and 10b in the pump are passed through to the low pressure priority shuttle valve 2, and the low pressure priority shuttle valve 2 is connected to the tank 5 via the tank ports 5a and 5b. ing. The in-pump working fluid passage 10a is continuous with the external working fluid passage A, and the in-pump working fluid passage 10b is continuous with the external working fluid passage B.
[0015]
Specifically, the low-pressure priority shuttle valve 2 is attached to and joined to the rear end surface of the pump body 1 as shown in FIGS. 1 and 3, and is connected to the pump body 1 by a bolt B2. Further, as shown in FIG. 7 which is a cross-sectional view taken along the line cc in FIG. 1, the body 21, a pair of check valve mechanisms 22, and a pin 23 are provided and are symmetrical. Note that FIG. 7 is a view seen from the back side, so in the following description, the left and right in FIG. 7 and the left and right in the sentence are reversed. Hereinafter, the left check valve mechanism 22 is referred to as a check valve mechanism 22a, and the right check valve mechanism 22 is referred to as a check valve mechanism 22b. The left check valve mechanism 22a includes a ball 24a, a sleeve 25a, a spring 26a, and a retainer 27a that also functions as a lid. An internal space 25a1 of the sleeve 25a communicates with the pump hydraulic fluid passage 10a. The right check valve mechanism 22b also includes a ball 24b, a sleeve 25b, a spring 26b, and a retainer 27b that also functions as a lid, and an internal space 25b1 of the sleeve 25b serves as the hydraulic fluid passage 10b in the pump. Communicating with That is, the in-pump hydraulic fluid passages 10a and 10b are communicated with the internal spaces 25a1 and 25b1 of the sleeves 25a and 25b, thereby penetrating the in-pump hydraulic fluid passages 10a and 10b to the low pressure priority shuttle valve 2.
[0016]
The operation of the low pressure priority shuttle valve 2 will be described with reference to FIGS. When the pump body 1 starts to push out (extend) the hydraulic cylinder 3 to the right, the working fluid flows into the internal space 25a1 of the left sleeve 25a, and the ball 24a is pushed out to the right. The ball 24a pushes out the ball 24b and the sleeve 25b together with the pin 23. At this time, the hydraulic fluid passage 10b in the pump communicates with the tank port 5b through the internal space 25b1 of the sleeve 25b. From the tank port 5b, if there is surplus hydraulic fluid, it flows out to the tank 5, and if there is insufficient hydraulic fluid, it is sucked from the tank 5. On the other hand, when the ball 24a comes into contact with the seat portion 21a formed on the body 21, the internal space 25a1 of the sleeve 25a is surely cut off from the tank port 5a, the pressure rises, and the working fluid flows out from the outflow port 1a. When the pump body 1 is operating in the opposite direction, the low-pressure priority shuttle valve 2 is also operated in the opposite direction. Further, when the pump body 1 is stopped, the pressures on both sides become equal, so that the balls 24a, 24b and the sleeves 25a, 25b are moved to the maximum left side and the maximum right side by the action of the springs 26a, 26b. It returns to the position just in the middle of the position moved to.
[0017]
At this time, since the hydraulic gear pump P is configured so that the pump main body 1 is provided with the hydraulic fluid passages 10a and 10b in the pump penetrating to the low pressure priority shuttle valve 2, the outflow ports 1a and 1b of the pump main body 1 are provided. Therefore, the distance between the tank 5 and the outflow inlets 1a and 1b can be shortened as compared with the embodiment in which the low pressure priority shuttle valve 2 is connected to the low pressure priority shuttle valve 2 via a rubber hose or the like. Accordingly, leakage of hydraulic fluid from the tank 5 to the pump body 1 can be reduced, and pressure loss can be suppressed, so that cavitation can be suppressed, noise generation and efficiency reduction can be suppressed, Stable operation can also be realized. Further, since the surplus hydraulic fluid is discharged to the tank 5 by the low pressure priority shuttle valve 2, the number of times the relief valves 4a and 4b are operated can be reduced, and the generation of noise accompanying the operation of the relief valves 4a and 4b can be reduced. Energy consumption can also be prevented.
[0018]
Furthermore, since the low-pressure priority shuttle valve 2 is connected to the pump body 1 and functions as an integral one, a valve having a check valve mechanism corresponding to the discharge amount of the pump body 1 can be selected. Accordingly, it is possible to prevent a malfunction due to a mismatch between the pump body 1 and the low-pressure priority shuttle valve 2. Furthermore, since the pump body 1 and the low-pressure priority shuttle valve 2 are configured as an integrated hydraulic gear pump P, space can be saved and costs can be reduced.
[0019]
The present invention is not limited to the embodiment described above.
[0020]
For example, in order to hold the load at that position during overload or when the pump is stopped, it is effective to place pilot check valves 7a and 7b in the passage A and the passage B as shown in FIG. Further, if the passages A and B are connected by the high-pressure priority shuttle valve 8 as shown in the figure, the single relief valve 4 can be used.
[0021]
Furthermore, the present invention can be applied not only to the hydraulic welfare lifter as described above, but also to hydraulic gear pumps used in various hydraulic equipment, cargo handling equipment, welfare equipment, etc. This can be used to reduce noise and save energy.
[0022]
In addition, various modifications may be made without departing from the spirit of the present invention.
[0023]
【The invention's effect】
In the present invention, the low pressure priority shuttle valve is provided in the gear pump, and the working fluid passage in the pump that penetrates from the discharge inlet to the low pressure priority shuttle valve is provided, so the low pressure priority shuttle valve is close to the discharge inlet of the gear motor. Thus, pressure loss can be suppressed, and cavitation can be made difficult to occur. Therefore, noise and energy consumption can be reduced and stable operation can be realized.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a hydraulic gear pump according to an embodiment of the present invention.
FIG. 2 is a front view showing the hydraulic gear pump according to the embodiment.
FIG. 3 is a rear view showing the hydraulic gear pump according to the embodiment.
FIG. 4 is a circuit diagram showing an example of use of the hydraulic gear pump according to the embodiment.
5 is a cross-sectional view taken along the line aa in FIG. 1. FIG.
6 is a cross-sectional view taken along line bb in FIG.
7 is a cross-sectional view taken along line cc in FIG.
FIG. 8 is a circuit diagram showing another example of use of the hydraulic gear pump according to the present invention.
[Explanation of symbols]
P ... hydraulic gear pump 1 ... pump body 11 ... casing 12 ... pump body 13 ... rear cover 14, 15 ... gears 141, 151 ... rotary shaft 16 ... movable side plate 17 ... bush 18 ... bush 1a, 1b ... outlet 10a DESCRIPTION OF SYMBOLS 10b ... Hydraulic fluid passage 2 ... Low pressure priority shuttle valve 21 ... Body 21a, 21b of low pressure priority shuttle valve ... Seat part 22a, 22b ... Check valve mechanism 23 ... Pin 24a, 24b ... Ball 25a, 25b ... Sleeve 25a1, 25b1 ... Inner space 26a, 26b of the sleeve ... Spring 27a, 27b ... Retainer 3 ... Double acting hydraulic cylinder 31 ... Bore chamber 32 ... Rod chamber 3a, 3b, 3 ... Cylinder outflow inlet 4a, 4b, 4 ... Relief valve 5 ... Tank 5a, 5b ... tank circuit 6 ... input shafts 7a, 7b ... pilot check valve 8 ... high pressure priority shuttle valve

Claims (1)

A double-rotating type having a pair of outflow inlets, comprising a pump body having the pair of outflow inlets, and a low pressure priority shuttle valve connected to a tank, and from the outflow inlet to the low pressure priority shuttle. A hydraulic gear pump characterized in that a hydraulic fluid passage in the pump penetrating to the valve is provided, and the low pressure side of the outlet / inlet of the pump body can be communicated with a tank.

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